Welcome to BikeForums.
Cycling as an adult can be fun, ..... after the break-in period - which varies with each individual. Lots of short easy rides.
Padded bike shorts for even the short rides.
When riding = ball of your foot on the pedal, not the arch or heel.
If your butt hurts lift it off the saddle more than occasionally. All the best riders do so.
Nice bike, btw. The place you bought from can help get saddle height correct. Maybe they even have saddles one might demo.
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Vintage, modern, e-road. It is a big cycling universe.